A driving chain for a bicycle, when stretched between the front chain gear and the rear chain gear, is covered by a chain casing to prevent a cyclist's clothes from being soiled by a lubricant fed to the chain. However, the chain casing is fixed to the bicycle frame, thereby being large-scale and taking much time to mount it on the bicycle frame. A full casing for covering the entire length of the chain is complicated to assemble, and a half casing for covering only the upper half of the chain stretched between the front and rear chain gears is still subject to the risk that the chain may soil the cyclist's clothes.
In order to solve the above problem, the present inventor has invented a cover for covering the chain itself, and this invention is the subject of Japanese Utility Model Application No. Sho 60-16,160. This application was filed only, but not laid-open.
The cover device in the above-cited Japanese Patent Application forms a plurality of covers, which are fitted on the link plates of the chain so as to cover them. The cover is provided with projections each engageable with the edge of each outer link of the chain and is mounted on the chain. During testing, it has been found that the cover constructed as described above can be easily removed when subjected to an external force and one widthwise end of each link plate is exposed from the cover, whereby the problem is created in that the chain may vertically swing due to vibrations of the bicycle to hit the chain stay.